1. Technical Field
The present invention relates to rehabilitation and therapy. More particularly, the invention relates to a system and method for rehabilitating visual defects. Specifically, the invention relates to a customizing a lens system with selective application of a translucent colored material to stimulate alternative visual pathways and restore vision in the defective areas.
2. Background Information
The condition known as hemianopia is a type of deficit in the visual field of humans where decreased vision or blindness takes place in half of the visual field of one or both eyes. The term hemianopia is Greek in origin, where “hemi” means “half”, “an” means “without”, “posit” means “seeing”. In most cases, the visual field loss respects the vertical midline. Thus the individual can properly perceive half of the field of vision in one eye, while the other half of that same eye suffers from a deficit in perception. Typically the eyes themselves are fully functional and not damaged. It is the pathways between the eyes and the brain that are damaged. The information routing and brain cognition of the information perceived by the optic nerve is not transmitted properly to the brain to form a correct and focused image in the individual's mind. The most common causes of this type of damage include stroke, brain tumor, and brain trauma.
The injury caused by any of the above incidents usually leads to varying degrees of inability to see in different parts of the visual field. The mechanism of transport of information from the eye to the brain in right hand dominant individuals is naturally designed to take images from left side of both eyes to right hemisphere of the brain and the right side of both eyes to the left hemisphere of the brain. Consequently, injuries in the right hemisphere of the brain cause difficulties in the left visual field of one or both eyes, and injuries to left hemisphere causes difficulties in the right visual field of one or both eyes. At times the damage is not bad enough to interrupt the patient's visual abilities significantly. At other times the deficit in the visual field is so extensive that it would cause total impairment of the half of the visual field of both eyes.
Since visual abilities are involved in many of physical and cognitive abilities of the person, this interruption of vision could potentially affect additional abilities of the person creating a unique syndrome for each individual. This syndrome could potentially include additional difficulties with visual memory, visual reasoning, hand eye coordination, ambulation, visual organization, and object naming. In many cases, the patient suffers from significant disabilities which permanently interfere with daily activities. For example, person's inability to see from the left visual field commonly known as “left sided neglect” could permanently prevent the person from operating a motor vehicle, as the person cannot see incoming objects on the road. Without the ability to operate a vehicle, in addition to the tremendous detriment to overall quality of life, the individual would also be deprived of many forms of employment.
There have been many attempts at trying to treat this condition. All of these previous attempts can be broadly categorized as utilizing either surgery or therapy. The utilization of surgery for treatment of hemianopia is quite limited and used only in rare cases. As such, the standard treatment method is therapy and rehabilitation. However, this treatment is typically focused on teaching the patient to learn to cope with the vision deficiency, rather than to restore the patient's vision. Rehabilitation is structured around behavioral methods, such as teaching the patient to pay extra attention to the area that they do not see naturally. Although these behavioral methods do have some value, these methods do not remedy the underlying problem. If affected individuals can learn to see and perceive objects properly, therapy and rehabilitation activities are unnecessary as the individual's quality of life is no longer affected by vision deficiency.
U.S. Pat. No. 5,886,769 to Zolten, U.S. Pat. No. 6,352,345 to Zolten, and U.S. Pat. No. 6,595,636 to Zolten, referred to hereinafter as the “Zolten patents”, relate to methods of making modifications to different visual devices to encourage healing of the brain without using any invasive techniques. The techniques discussed in the Zolten patents are known in the field as “visual constraint therapy” for treating hemianopia. Under this method of treatment, parts or the entire healthy portion of the visual field is completely blocked by using different methods of obstructing the visual field through glasses, lenses or other devices. Visual constraint therapy places an emphasis on obstructing certain areas of visual field to encourage the brain to develop new neural pathways for connecting the eyes and the brain, thus allowing the patient to see objects in the affected areas. This obstruction may be either complete or partial with respect to coverage of the visually defective areas of the visual field. Over time, the obstruction of the visual field is increased or decreased in size for rehabilitation and neural training purposes.
Visual constraint therapy and the related patents do not consider the use of a translucent obstruction over the healthy portion of the visual field. While the Zolten patents disclose the use of “degree[s] of opacity” and “semi-opaque” occlusion of the visual field, the percentages of opacity are referenced with respect to the overall area of the radial segments or visual obstruction areas. Zolten consistently utilizes occlusion over the healthy portion of the eye, such that visual light cannot pass therethrough. While the overall size may be expanded or reduced over the course of treatment, visual constraint therapy completely occludes the intended area of the visual field.
Although there have been many claims of success utilizing this technique, visual constraint therapy has not been able to provide enough success to be accepted as an effective treatment for hemianopia. Also, in practical terms, the obstruction of a portion of the patient's glasses or lenses could be risky as the patient is deprived of most of their vision until they adapt to the device. As such, most patients find visual constraint therapy unsettling and either never begin the therapy or discontinue treatment before any benefits can be realized. Patients who remain in treatment and are willing to use the device, find that the blockage of the visual field is cosmetically undesirable as the patient stands out in public. This leads embarrassment and negative feedback. Thus, patients typically only use the device in private, which results in patients experiencing only minimal gain and limited visual restoration.
Furthermore, visual constraint therapy attempts to build new neural pathways for connecting the optic nerve to the brain centers used to process visual input. This type of biochemical restructuring is a very slow and unreliable process. As such, visual constraint therapy takes a tremendous amount of time before results are realized. As discussed above, patients are already reluctant to wear unsettling and cosmetically undesirable devices. When patients do not experience results after months of therapy, the patients typically get frustrated and discontinue the treatment.
Confronting the above facts, there is a tremendous need in the field to provide an easily reproducible and non-invasive system and method for the treatment of hemianopia. The system and method should not be unsettling to the patient, and should be cosmetically appropriate for public use, such that the individual will maintain treatment throughout the individual's normal daily routine. Furthermore, the system and method involved should result in a relatively quick restoration of vision in the defective areas.